Chord Extension Ear Trainer
Hear the colour note. Identify the 9th, 11th or 13th sitting on top of a seventh chord — and the added-note chords, 6 and add9, that get there without a 7th at all.
The idea
A seventh chord is the skeleton. Stack another third on top and you get the 9th; another and the 11th; another and the 13th. Those upper notes do not change the chord's function — they colour it. This trainer plays one chord and asks you to name which colour note is sitting up there.
The A / B compare button is the heart of it: it plays the plain base chord first (a triad, or a plain 7th / maj7 / m7), then the same chord with the extension, on the same root, back to back. Everything you hear that is different between A and B is the colour note.
Controls
- Play chord — plays the round's chord. Once you have heard it the label becomes Replay. Audio hardware is only opened on this first click, so nothing autoplays on page load.
- A / B compare — base chord, short gap, extended chord. Works before and after you answer. After you answer, the stack diagram lights the colour note exactly when the B chord sounds.
- Next — new random chord from the pool, new random root. Enabled once the current round is answered.
- Answer grid — click or tap the chord you think you heard. It shows every chord in the pool at once; nothing is hidden behind a scrollbar.
- Pool presets — Start, 9ths, 11 & 13, Altered, All. Below them, every chord chip toggles individually; a hollow dashed chip is out of the pool. Two chords is the minimum.
- Playback — Block plays all notes together; Arpeggio rolls them bottom to top, sequenced on the audio clock so it stays even.
- Master volume — per-note gain is also divided down by the number of voices, so a six-note chord does not clip.
- Auto-play the next chord — when on, moving to a new round plays it straight away.
- Reset everything — score, streak, per-extension stats and the pool go back to defaults.
- Fullscreen — expands the widget; the button relabels to Exit fullscreen.
Keyboard
- Click the widget once so it has focus, then: Space play / replay the chord.
- Enter next round. C runs the A / B compare.
- 1–9 answer with the first nine buttons in the grid (their number is printed on the button). Larger pools need a click for the rest.
- ↑ / ↓ master volume. Arrow keys are left completely alone while a slider or any input has focus, and Space / Enter are left alone while a button has focus.
Formulas — semitones above the root
Note add9 against 9: add9 is a plain major triad plus the 9th and contains no 7th at all (0-4-7-14). A 9 chord is a dominant 7th with the 9th on top (0-4-7-10-14). That missing ♭7 is the whole difference and it is very audible once you know to listen for it.
How these chords are voiced (and what gets left out)
- The root is played in the bass, and every other note is voiced in the octave above it, so the 9th, 11th and 13th genuinely sound in an upper register instead of being crammed into one octave.
- On any chord of five notes or more the perfect 5th is dropped. It carries no colour, it eats headroom, and on a 7♭13 it sits a semitone below the ♭13 — keeping both is what makes that chord sound wrong. On 7♯11 the ♯11 has effectively replaced the 5th anyway.
- On the 11 chord the major 3rd is dropped instead. A natural 11th one semitone above the major 3rd is the classic clash, which is why a working musician plays C11 as a G minor 7 over a C bass — and why on a dominant or major chord the 11th is normally either omitted or sharpened to ♯11. The formula 0-4-7-10-14-17 is still the textbook spelling; the voicing simply leaves the 3rd out.
- A 13th chord in practice drops the 11th. That is already baked into the formulas here: 13 is 0-4-7-10-14-21, with no 17 in it. Same for maj13.
- Minor chords have no such problem: on m11 the 11th sits a whole tone above the ♭3, so it stays, and only the 5th comes out.
Tips
Start with the Start pool and use A / B on every single round for the first ten minutes. The 6th and the add9 are the easiest pair to separate: the 6th sits inside the chord and sounds sweet and closed, while the 9th floats above it and sounds open.
For the altered pool, stop trying to name the interval and name the flavour instead: ♭9 is tense and dark, ♯9 is the gritty blues/Hendrix rub against the major 3rd, ♯11 is bright and glassy, and ♭13 is heavy and sour. Switch to Arpeggio when a chord will not resolve for you — hearing the top note arrive last usually settles it.
The aim of this ear trainer are to get you identifying which ‘colour’ note makes the harmony. It plays a chord then asks you to identify specific colour note that defines it. With your computer keyboard, you can navigate around quicker or just click on buttons that appear on your screen.
To play with the app, select a level from one of the options above: Chords in all keys; Triads; Dominants; Major sixths; Added ninths, or Various dominants. To get started, hit the Play chord button (above) and listen to the chord in the first example. The app use an audio engine that needs a trigger to start playing, so you’ll notice it doesn’t make any sound until you do something.
How to Use the Ear Trainer App
After you’ve heard the chord, use your mouse to click button on the grid below the transport controls that corresponds to the one you believe it is. Alternatively, simply hit the Space bar to play, or replay if necessary, the current chord. It will then highlight your selection as right or wrong and show you actual answer.
Most useful for learning are the buttons marked A / B (compare) since these plays the plain base chord then the extended one, so you can just hear the difference between them. Make sure you listen carefuly for the second half of comparison where you will hear that additional note. This is the extension you’re after.
Below the answers, you’ll see a stack diagram which show the structure of the chords. It colours the note that adds the extension, highlighting it precisely at the point where the extended chord sounds in comparison. So, there’s a visual clue here that connects what you’re hearing to the underlying theory behind the chord.
The pool controls allows you to tailor what is shown and how hard it is. A bank of preset buttons allow you to change the selected group, like Start for beginning players, 9ths, or even Altered chords if you want to work more on that. If you see something that’s particularly tricky to play, you can turn those off individually in the pool grid until only the ones you’re having trouble with is left. Keep in mind that the tool requires several different options to be available to create an appropriate question. The interface won’t let you clear too many out so that nothing can be played. Tweak it to match your learning needs.
There are two different playback modes. Block sounds all the notes together, like many chord do in mixed pieces. Arpeggio rolls the notes up from bottom to top, allowing you to easily identify what each note is and how high it sit.
You’ll also find a handy slider for Master Volume that lets you make this as loud or quiet as suits you. You can also use the Up and Down arrow keys on your keyboard to rapidy increase or decrease the volume.
Finally, there’s an Auto-play option that you can toggle on or off to play the next chord after you’ve answered, so your practice session doesn’t stop. It flows more quickly and smoothly thanks to keyboard shortcuts. Press Enter to answer a round and move to the next one. Anytime you want to hear the A / B comparison play out yourself, use the C key. If you’re sure of what you’ve heard, you can even answer with a numeric keypress between 1 and 9, each corresponding to the first nine buttons on the answer grid.
And lastly, the help button at the bottom opens up an expanded panel that shows the voicing rules and formulas for reference. Use the breakdown panel and score to keep up on your work. The main score section show your current and best streaks, along with your overall accuracy. This lets you easily follow your improvement over time. In the per-extension accuracy breakdown, you can see what kind of accuracy you’re getting with certain chords and where you might have some weaknesses that require more focus. Use the reset button to reset your stats and put the pool back to its default settings if you would of liked to try again.
With the comparison function, spend some time on every chord. Initially, you’ll find that certain textures can be hard to tell apart, for example, the open nature of an added ninth in contrast than the sweet-sounding sixth. If you’re not sure about a chord, flick into the arpeggio view, you’ll often hear how the top note sounds when it finally comes which will help clear up any confusion.
To minimize distractions and leave a larger area of the screen for the interface, there’s a fullscreen option too. The preset pool is a good place to begin and then add increasingly complicated chords as you become more comfortabley.